Cornea wounds can lead to scarring, hazing, and subsequent vision loss. Several biochemical signals, including extracellular nucleotides and growth factors play key roles in activation of wound healing programs. The discoveries of the molecular identities of wound induced signals prompted the development of therapies that aim to prolong the natural healing programs in order to minimize the danger of injury induced vision loss. However, these therapeutic approaches had only limited success. The lack of a detailed quantitative mechanistic understanding of the regulation of these paracrine signaling molecules prevents the critical assessment of current therapies and the development of the next generation of quantitative systems pharmacology therapeutic approaches. The goal of this work is to determine the regulatory mechanism that controls the spatio-temporal propagation of two key paracrine signaling molecules: ATP and HB-EGF. Each plays an essential role in the activation of wound healing programs. This proposal will capitalize on a novel microfluidics-based wounding platform we recently developed. The new device enables highly controlled wounding of epithelial monolayers without any fluid mixing and thereby generates real-time data of the spatio-temporal propagation of the Ca2+ and Erk pathways. We will use the new device in synergy with multiple computational approaches to dissect the paracrine signaling regulatory network that controls the propagation of wound induced signals. The specific aims are: (1) Elucidate the mechanism that controls the spread of initial ATP signals. (2) Dissect the mechanisms responsible for the spatial propagation of Erk pathway activation. (3) Determine the function of paracrine signals in reducing the noise in Erk pathway activation. In aims 1 and 2 we will construct and independently calibrate multi-scale tissue-level models that combine intercellular ATP and HB-EGF dynamics with intracellular the kinetics of Ca2+ and Erk pathway activation. The models will be used to test multiple hypotheses on the mechanism that controls the spatio-temporal propagation of ATP and HB-EGF signals to activate wound response signaling. In aim 3 we will use an information-theory approach to analyze test how the identified mechanisms contribute to the generation of a robust spatial distribution of Erk activation. The successful completion of these aims will close an important knowledge gap on the complex mechanism that regulates the activation of wound healing programs. The predictive mathematical models that we will construct and experimentally corroborate will provide an important tool in the design of future therapies that aim to augment existing wound healing programs to prevent vision loss due to corneal injury.